Condensation of formaldehyde with ketones and nitroparaffins



June 6, 1950 H. M.

coNDENsATIoN 0F FORMALDEHYDE WITH SPURLIN 4 1 Gus. 0 l v5, 2

KETONES AND NITROPARAFF'INS 2 Sheets-Sheet 1 Filed Nov. 24, `1945 JOKPZOU Il INVENTOR,

M f., PM

June 6, 1950 H.^M. sPURLlN CONDENSATION 0F FORMALDEHYDE WITH KETONES AND NITROPARAFFINS Filed Nov. 24, 1945 PUDOONE ZOTCQWZMOZOU I OJLPMEOZOE INVENT( )1'\'. Haro/o M. lour//n Swat Pm Patented June 6, 1950 UNITED STATES PATENT OFFICE CONDENSATION OF FORMALDEHYDE WITH KETONES AND NITROPARAFFINS Harold M. Spurlin, Marshallton, Del., assigner to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Application November 24, 1945, Serial No. 630,666

13 Claims. 1

This invention relates to aldol-type condensations and more particularly to the condensation of formaldehyde with aliphatic ketones and nitroparafns.

This condensation is well known to the art, but a great deal of difficulty has been experienced in the production of monomethylol reaction products. It was originally thought, for instance, that acetone and formaldehyde condensed to form 3ketobutanol in high yields, but subsequent inlo progressively richer in S-ketobutanol content and vestigations have demonstrated that the condenleaner in formaldehyde as it descends through sation was far more complex than lrst described. the column. The formation of secondary prod- Actually, it has recently been established that at ucts is in this Way hindered. Upon completion least live products result from this condensation of the condensation the water and excess acetone and that the large number of by-products limits l5 are removed from the crude reaction mixture by the yield of 3-ketobutanol to about 27%. This distillation at reduced pressure, and fractionation fact is in contrast to the yields shown for various of the residue results in a high yield of 3-ketoprior art procedures which claimed to increase the butanol. yield of 3-ketobutano1 by increasing the ratio of Figures 1 and 2 in the accompanying drawings acetone to formaldehyde and by controlling the illustrate apparatus and procedures by which the pH of the reaction mixture.V The high yields preprocess of this invention may be carried out. The viously recorded were undoubtedly due to the apparatus shown in Figure 1 is for the batch presence of large amounts of secondary products method of producing the monomethylol reaction which were not separated from the 3-ketobutanol products. Storage tanks l, 2, 3 and 4 contain and which were, therefore, unknowingly conthe reactants and reagents used in the process; sidered as 3ketobutanol itself. Although the namely, the alkaline catalyst solution, the formcondensation of acetone and formaldehyde has aldehyde solution, the ketone or nitroparain, been discussed specifically, the same situation and the solution of acidic material used to neuexists generally in the condensation of formtralize any alkaline catalyst reaching heating aldehyde with other aliphatic ketones and also pot 9. with hierop-gramm, The alkaline catalyst and formaldehyde solu- Now, in accordance with this invention it has tions are blended by means of the plate mixer 5, been found that formaldehyde may be condensed passed through DH control 6. in Which the 10H with a, liquid Organic Compound Selected from the Of the alkaline 50111171011 S determined all regular group consisting of aliphatic ketones and nitrointerValS, and then through metering valve 'l into paraiiins by reuxing the aliphatic ketone or the 130D Of fractonating column IS. The ketone nitroparain in a fractionating column below the 01 htrOpal'afIl may either be Charged into heatcolumn flood point while simultaneously passing ing P01? 9 0r passed thrOllgh metering valve 3 into formaldehyde and an alkaline catalyst downward the top of fractionating column l0, although only through the column. The process operates on the 4.0 the former procedure is necessary in the event principle of true countercurrent action of the a batch technique is utilized. As will be shown reactants and the column functions in the dual in the examples, however, it often is desirable to capacity of a reaction tower and a fractionating charge heating pot S with a portion of the ketone column. or nitroparafn and later add additional amounts In practicing the process in accordance with of either of these components through valve 8 into this invention, acetone and formaldehyde, for the top of column lll. example, may be condensed to give high yields Heating pot 9 is charged with the selected of S-ketobutanol by refluxing the acetone in a ketone or nitroparaiiln, and by utilizing any suitfractionating column, operating the column below able standard source of heat the ketone or nitroits flood point while simultaneously adding paraffin is vigorously refluxed in column I0 while Formalin, adjusted to a pH of about 10 with the formaldehyde and alkaline catalyst solution aqueous sodium hydroxide, at the top of the is metered into the top of the column using metercolumn. The Formalin feed entering the top of ing valve 1 as the regulator for rate of introducthe packed column is accurately metered and this, tion. Column l0 is operated below its flood point, in conjunction with operation of the column and condenser Il prevents vapor losses. Through ration of the product and excess reactants, as by flash distillation, to prevent undue heating of the former and consequent possible decomposition, although the total crude reaction product may be immediately subjected to reduced pressure distillation with satisfactory results..

Figure 2 represents apparatus for the continuous production of the monomethylol condensation products. The process described-in connection with Figure 1 is duplicated upto the point of collection of the product in pot 9. In 1 thecontinuous process the product is continuouslyI-.withdrawn from pot s intov storage tank I2, from4 which it is led into the center section of distillationcolumn. I3. In the latter the excess reactantsare flashed oli, condensed by condenser L.

I4 andA returned to the condensation reaction zoneA through recycle I5. The monomethylol product .passes from the bottom ,of column I3 intostorage I6, from which it may be withdrawn for lthe final fractional distillation under reduced pressure. In the continuous process. additional ketone or nitroparain ischarged into ,the top of column I .toreplace reaction loss.

The apparatus may be further modified in order. that the alkaline catalyst solution contained in storage tank I may be .blended with cer tain ofthe-ketones or nitroparans stored in tank 3. one goingv directly to .pot 9 for charging purposes. The other outlet passes through the system represented byf5,.., and 1. When the catalyst is addedby .thismeans, the formaldehyde is passed through meteringyalve E directly into column III.y

They general embodiments of this invention having been. outlined, the. following examples constitute specic illustrations. All parts are.

based on parts by weight.

Example I The apparatus usedin this example was. essentially that shown in Figure l. A batch procedure` was carried-out and the catalyst added in conjunction .with the ketone, Column III was a packed column of sufcient size to permit a ratio of methyl ethyl ketone to formaldehyde of at least. 30 to 1 in the reaction zone at .the top of the. column. Heating pot 9 was charged With '12 parts of methyl ethyl ketone and 5.2 parts of 10% citric acid-solution, the charge thenbeing heated to 73.5 C., the boiling point of the watermethylv ethyl ketone azeotrope. By properly adjustingfthe-pot temperature (73.5 to 95 C.) and the temperature of the column the latter was operated atv high reflux but below its flood point. Through metered valves 1 and 8 over a period of.. four hours there then were added simultaneously '12 parts of methyl ethyl ketone con!l In this case tank 3 has two outlets,-

then was distilled in vacuo through a packed distillation column. After a forerun of .Water and unreacted methyl ethyl ketone there was co1- lected 93 parts (91% based on formaldehyde) of Z-rnethyl-S-ketobutanol, boiling at S30-93 C. under a pressure of 20 mm. of mercury. The ketobutanol had a refractive index of 1.4320. at 20 C.

Example II The apparatus used in this example was that shown in Figure 2. The fractionating column I0 :wasa packed column which permitted a ratio of methyl ethyl ketone to formaldehyde of at least .30. to l in thereaction zone at the top of the. column. Heating pot 9 was charged with 108 parts. of methyl ethyl ketone and 10.4 parts of 10% citric acid solution, the charge then being heated to '13.5V C., the boiling point of the Watermetliyl ethyl ketone azeotrope. By properly adjusting the pot temperature (73.5 to 95 C.) and the temperature of-the column, .the latterV was `operated at high reflux but below its. iiood point. Through valve 1 over. a period of y9&1 minutes. there then was added 81 parts of 37% Formalin..adjusted to a pH of v10.5-with aqueousr sodiumhydroxide.

Through valves 1 and 8 during the next. five hours there were added simultaneously .284 parts of 351% Formalin at a pI-I of 10.5 'and3'18 parts of methyl ethyl ketone. Throughoutthigtime the crude reaction mixture contained in heating.

pot and consisting of vmethyl ethyl. ketone1 wa. ter and 2-methyl3ketobutanol was drawn off into storage tank I2 at a rate-proportional to the rate of additionof the reactants. Also., dur.- ing this time thepH of the mixtureinthe pot was maintained at 4.6-5.1 by adding small quan.- tities of 10% vcitric acid solution from storage tank d.

The crude reactionmixture (pI-l'. of 5.0) was continuously'transferred from storage I2 yto column I3, inwhich ashdistillation removed 558 parts total of' water and excess methyl ethyl ke,- tone, the latter lon condensation in condenser IB being returned by recycle -I5 to thereaction zone..

The 2-methyl-3-ketobutano1*was drawnfrom the bottom of column'I3 into-storage 4I 6, -fromwhich it finally was withdrawn and-distilled in-;vacuo.

Therewas obtained 39'1.parts. (86%. based on.

formaldehyde). of 2-methyl-3-ketobutanol, boiling at 92-95 C. under a pressure voff20 mm.. of mercury.

Example III there was .added 3130 parts of 36%?`r'onnelin,

adjusted-,to a pHof 10.5 with aqueous sodium hydroxide, through metering valve 1.1 The excess ketone then was stripped oijncolumn I0; and

in thismanner 3100v parts -oi Lunreacted ketone.

was recovered.

The aqueous ypot residue .thenwas 'distilled under reduced pressure to remove the Water. Finally.. by further distillation under reduced pressure 336.0 parts, (88%.' based 'onformaldehyde) of 2`rnethyl3ketobutano1, boiling at 90- 93 C. under a pressure of 20 mm. of mercury was obtained.

Example IV The apparatus used in this example was that shown in Figure 1. The fractionating column l0 was a packed column of suiiicient size to permit a ratio of acetone to formaldehyde of at least 55 to 1 in the reaction zone at the top of the column. Heating pot 9 was charged with 174 parts of acetone and 5.2 parts of 10% citric acid solution. The column was adjusted to operate under high reflux but below the column flood point. The temperature varied from 56.3o to 85 C. in the heating pot as the reaction progressed. Through valve l during a period of 2.5y hours there was added 33.5 parts of 36% Formalin, adjusted to a pH of 10.2 with aqueous sodium hydroxide.

The reaction mixture was distilled under reduced pressure to remove the excess acetone and water. Subsequent fractionation of the residue in a packed vfractionating column gave 13.3 parts of diacetone alcohol, boiling at 62-68 C. under a pressure of 12 mm. of mercury and having a refractive index of 1.4235 at C., and 74.1 parts (84% based on formaldehyde) of S-ketobutanol, boiling at 73'l6 C. under a pressure of 12 mm. of mercury and having a refractive index of 1.4290 at 20 C.

Example V The apparatus used in this example was that shown in Figure 1. Pot 9 was charged with 430 parts of diethyl ketone and 0.5 part of citric acid in the form of monohydrate crystals. Column l0 was a packed column adjusted to operate under rapid reiiux but below its hood point, and over a period of ve hours there was added 100 parts of 36% Formalin, adjusted to a pI-I of 10.5 with aqueous sodium hydroxide, through valve l. After all the formaldehyde had been added the crude reaction mixture was adjusted to a pH of 7 with 10% citric acid solution from storage 4 and most of the excess diethyl ketone distilled off at atmospheric pressure. Fractional distillation was then eiiected under a pressure of mm. of mercury, resulting in the collecof 2-methyl-S-ketopentanol, 111 C.

Example VI The apparatus used in this example was the same as that in the preceding example. The internal pressure of column l0, however, was maintained at 120 mm. of mercury and under these conditions the nitromethane utilized in this example boiled at 52 C; Heating pot 9 was charged with 183 parts'ofnitromethane and 5.2 parts of 10% citric acid solution, and the co1- umn was adjusted to operate under high reflux but below the column flood point. The temperature varied from 52 to 80 C. in the heating pot as the reaction progressed. Through valve l during 2.5 hours there was added 8l parts of 36% Formalin, adjusted to a pH of 10.0 with aqueous sodium hydroxide. Upon completion of the condensation the reaction mixture was neutralized to a pH of 7.0 with 10% citric acid solution and then distilled under reduced pressure. After a forerun of nitromethane and water there was collected 58.6 parts (64% based on formaldehyde) of Z-nitroethanol, boiling at 95- 99 C. under a pressure of 8 mm. of mercury.

parafns which are operable.

Although the examples have shown the condensation as applied to acetone, methyl ethyl ketone, diethyl ketone and nitromethane, various other aliphatic ketones and nitroparains may Ibe utilized in the process of this invention. Additional ketones include methyl isopropyl ketone, methyl propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, ethyl propyl ketone, ethyl isopropyl ketone, and the like. Nitroethane, nitropropane, l-nitrobutane, 2- nitrobutane and the like are additional nitro- The ketones and nitroparafiins should be liquids having moderately low rboiling points, preferably not more than about C., although higher boiling compounds may be used according to the process of this invention. As illustrated by Example VI it may be desirable to lower the boiling point of normally high boiling compounds by reducing the pressure within the fractionating column. It is apparent that pressures lower than that shown in Example VI may be used, depending on the compound involved. Higher pressures also may be utilized, even above atmospheric, if the nature of the contemplated reaction so requires.

When operating the process according to the procedure shown in the examples, namely, using an aqueous formaldehyde solution, it is preferable that the aliphatic ketone or the nitroparain have a boiling point lower than that of water or form an azeotropic mixture with water which is rich in the ketone or nitroparain. These conditions are `desirable since they insure thorough reaction of the ketone or nitroparailin with the aqueous formaldehyde solution at the top of the column. It is not necessary, however, that such conditions be followed, since the formaldehyde may be dissolved in a solvent other than water, in which case it is not necessary to take into account the boiling point limitation imposed by the presence of water in the reaction mixture.

The examples have shown the use of formaldehyde in the form of an aqueous solution but, as has been indicated, the formaldehyde may be added in solution in other solvents which are unreactive in the condensation reactions. Either monomeric formaldehyde or its polymers may be utilized in accordance with this invention.

Sodium hydroxide has been shown as the alkaline catalyst in all of the examples, but potassium hydroxide, sodium carbonate, potassium carbonate, sodium etliylate and the like also may be utilized. Other catalysts having suflicient alkalinity and solubility in the reaction medium are operable. The lconcentration of the alkaline catalyst solution is preferably about 10%, but the concentration may range from about 5 to about 15%.

One of the factors which governs the yield of the monomethylol compound obtained is the pH of the catalyst-containing solution added to the reiiuxing ketone or nitroparaffin. Generally speaking, high yields may be obtained when the pl-I of the solution containing the formaldehyde and the alkaline catalyst is between about 9 and about 11. In the case of the condensation of formaldehyde with acetone the pI-I preferably is between about 9 and about 10.5 and `a, range of about l0 to about 10.5 is particularly applicable. In the condensation of formaldehyde and methyl ethyl ketone the preferable pH range is from about 10 to about 11 and about 10.5 to about 11 is most desirable. For the sake of convenience the proper pH is most conveniently obtained bydissolving the alkaline catalyst in theaqueous formaldehyde solution, but, as shown in Example I,.the catalyst may -be added 'in solution .with the fketone providing Athe catalyst does not vcause the-ketone to condense. with itself. Generally speaking 1.7 parts of lsodium hydroxide solution will bring 8l parts of 36% Formalin to a pH of 10.2 and 2.2 parts of 10% sodium hydroxide will give 81 parts of 36% Formalina pH of 10.5. All pH measurements were made with a Beckmann pH Meter, Industrial Model, .utilizing a glasselectrode adapted for use Vwith alkaline solutions.

All of the examples have shown the use .of citric. acid to neutralize any of the basic catalyst which reaches the reaction-p-ot. The citric acid may be utilized either in .the form of a .solution or as the crystalline material. Preferably some -of the acid initially is charged into the reaction pot, and further additions made as they are needed during course of the condensation. The purpose of ,this neutralization is to prevent/further ycondensation of the monomethylol products with any formaldehyde reaching the pot, and to hinder the dimerization of ketones when they are reactants. Acidic materials other than citric acid maybe Vusedfor thispurpose providing they have nodeleterious eiect, suchas dehydration, on the monomethylol'condensation products. Preferablythey also. should be nonvolatile. Sodium bisulfate, for example, may be usedin place of `citric acid. The-concentrationofv the acidic material preferably is about 10%, but the-range may extend from-about 5% to about 15%.

One ofthemost desirablefeaturesof the vproc-l ess of this invention isA that fact thatv it` provides a means` of having-an excess ofthe ketone or nitroparailn--in .the main vreaction zoneat the top of the column while continuously providing for-the--removal of the monomethylol substitution product. Tlere is a certain ldesirable minimum excess4 of each ketone and nitroparafn, as .come paredvtoformaldehydewhich will result. in the formation of an optimum yield of the corresponding lmonomethylol product, .and this excess is controlled by the rate ofV additionvof the formaldehyde.V It is apparent, howeventhat the ratio of ketone vor nitroparaihn to formaldehyde Will also depend to some extent upon Athe size of the reaction column used. Generally, the length..o the column should beat least aboutsix times its diameter, although longer-columns :are satisfactory. Inthe condensation of methyl ethyl. ketone with formaldehyde the flatter .should preferablybe :added at such arate that. the .ratio of methyl ethyl ketone to formaldehyde is at least-*30.130 l in the main reactionzone .at the top of the column. With acetonetheacetone -to formaldehyde ratio should beat least 55 to 1 in this `reaction zone. The acetone to formaldehyde ratiois approximately twice the methyl` ethyl ketone to formaldehyde -ratio because acetone has-six active-byey drogensequally able to react Wih formaldehyde, Whereas mehyl'ethyl ketone only has two. Furthermore, the monosubstitution product `of-ace-A tone still hastWo active hydrogensv on the methylene group adjacent to the carbonyl. group, while the v.rnonosubstitution productof methyl ethyl ketone hasonlyone In other Words, 'it is apparent that .the number and relative activity `of the active hydrogen ,atoms in the ketone or nitro` parain 'determines to someextent -the excess or these compoundsfwhich is required.

Fractionating columndl) may I. be a packed, bubbleeplate, baiflefplate or like` fractionating column. .A-.packed.column.may contain Y variouspackings,l but. should` vadhere tocertain specifi cationsin size. Ona laboratory scale, the column may be packed With glass beads, glass or. stain-y less steel helices, etc.,..but a commercial column will preferably employ Raschig rings made of glass, porcelain or some other material not corroded by the reactants. Distillation column I3 may be similarly packed. The reaction column I0 should have a length at least about six times the diameter in order to provide suicient volume to permit the-'desiredl excess of ketone ornitroparainas compared -to formaldehyde, but longer columns are operable and Ausually are actually used. The column may be electrically heated, and in this manner the temperature controlled Very accurately so that the column operates beloW its flood point for each particular ketone or nitroparailin. Steam, superheated steam,'oil and Dowtherm may be utilized, however, for heating the column. The same heating media maybe used in connection with heating pot 9.

In packed columns the gas and liquid velocities for countercurrent operation are limited by the tendency of the column to flood at high rates of either gas or liquid. As either gas or liquid velocity is gradually increased, the liquid holdup in the packing is increased, and a point is finally reached ,Where the pressure drop rises sharply with even a slight increase in gas velocity. Entrainment of liquid inthe gas leaving the tower also increases sharply. This point is called the nood point. In the process in accordance with this invention it would not be desirable to operate ator above the flood point, because. of loss of material and decreasedrectication, but by operating, below the flood point` a large excess of the ketone or nitroparafiln in the reaction Zone.

is insured while at the same time Aitis possible for the column to remove the monomethylolsubr,

stitution productas, it is formed. By Ithe latter action the monomethylol compound is prevented from remaining vin the region of highest formaldehyde concentration. Even though the formaldehyde concentration at its highestk is slight. in.

comparison to the amount of ketone, or nitr.0- parailln present,.nevertheless continuous. removal of the monomethylol condensation product prevents further condensationof the latter with additional formaldehyde and constitutes one -of the basic advantages of thev process.

In case it is desirable to convert the monomethylol substitution products to the corresponding vinyl compounds this may be accomplished by radding the monomethylol product dropwise to a reaction pot containing adehydration catalyst and anexcess of water at its boilingpoint` In the case of 3-ketobutanol and 2-meth-yl-3 ketobutanol, for-instance, these -ketonealcohols undergo aa molecular splitting out Yof Water to form the corresponding Vinyl ketones, methylv vinyl ketone and methylA isopropenyl ketone, re spectively; which may be distilled in the form .of their azeotropes with water through a fractionating column attached to the reaction pot. The methyl vinyl -ketonewater azeotrope is hornogeneous, vWhereas thecorresponding azeotrope ,of methyl isopropenyl ketone is not. The latter separatesinto two layers on cooling', consequently it is possible by use of an automatic separator to return the Water layer to the distillation ask.

Iodine is an efcient dehydration catalyst, `but other catalysts which are operableincludeyorthof:

phosphoric, sulfuric, hydrochloric,v oxalic,'lpf toluenesulfonic, and y-naphthalenesulfonc4 acids; In the case-of sulfuric acid. it. is desirable con currently to use an inhibitor such as sulfur, hydroquinone, or tert-butyl catechol. Both methyl vinyl ketone and methyl isopropenyl ketone may be puried by redistillation. The former, being miscible with water in all proportions, may be redistilled in the form of its azeotrope, which contains about 7-8% water. The anhydrous ketone then may be prepared by removing the last traces of water by physical means, such as freezing or azeotropic distillation with a third component. Methyl isopropenyl ketone may be dried by simple distillation or by freezing out the excess water.

The process in accordance with this invention provides for a very large excess of the ketone or nitroparafn in the reaction zone at the top of the reaction column and for the continuous removal of the monomethylol reaction pro-duct from the reaction zone. Because of the latter effect an improvement is obtained over prior art processes which utilize large excesses of the ketone or nitroparafiin but which do not prevent further condensation. The process also is advantageous in that the formation of ketone dimerization products such as diacetone alcohol is hindered by reversal of the equilibrium between the ketone and its dimer at some point lower in the reaction column. The equilibrium is reversed in favor of ketone formation, thereby preventing accumulation of the dimer as a byproduct. This is particularly true when the dimerization reversal is more rapid than the formaldehyde-ketone condensation. The process also is advantageous in that it provides a means of neutralizing the alkaline catalysts in such a manner vthat the latter will not catalyze condensations which are not desired.

The yields of monomethylol substitution products obtained in accordance with this invention are superior to those obtained utilizing only the principles of high dilution. Numerically speaking a yield of about '70'to about 90% of Z-methyl- S-ketobutanol actually is obtained as compared with the 68% which is claimed by prior art processes. Similarly, 3-ketobutano1 is obtained in yields of about '70 to about 85% as compared with the 27% lately shown to. be the maximum using prior art procedures. Because the monosubstitution products are obtained to the virtual exclusion of undesirable secondary reaction products, the process is not encumbered by purification problems. Furthermore, although within the reaction zone at the top of the column the ratio of ketone or nitroparain to formaldehyde is high, in the overall reaction the ratio of the total amount of ketone or nitroparafiin to the total amount of formaldehyde used is quite low. In this respect the ratio of methyl ethyl ketone to formaldehyde may be as low as about 1.5 to 1 as compared with the 4 to 1 ratio required by previous procedures. Similarly, an acetone to formaldehyde ratio of about 2 to 1 may be utilized as compared to 4 to 1 by other methods, and a nitromethane to formaldehyde ratio of about 3 to 1 is possible as compared to the 10 to 1 required by the prior art.

The process of this invention therefore requires less ketone or nitroparaiin than do previous processes, yet makes possible attainment of desirable high ratios of these compounds to formaldehyde in the reaction zone at the top of the reaction column. The commercial advantages of the process are immediately apparent. Outstanding yields of the monomethylol condensation products are obtained, and operational costs are lil markedly reduced. In the latter regard the use of relatively small amounts of ketone or nitroparanin in comparison to formaldehyde, and the necessity for recovering only small amounts of excess ketone or nitroparafn upon completion of the condensation reaction are of prime importance.

The monomethylol compounds obtained in accordance with this invention are useful as solvents for cellulose derivatives and in the preparation of lacquers. The corresponding vinyl compounds, such as methyl vinyl ketone and methyl isopropenyl ketone, derived from the monomethylol compounds may be polymerized either alone or in conjunction with other polymerizable compounds to obtain highly useful polymeric materials.

The term fractionator,7 as used in the claims attached hereto, is used to mean either the combination of a fractionating column with a separate heating pot as shown in Fig. 1 and Fig. 2 hereof or the type of fractionating apparatus commonly used commercially which consists of a fractionating column so constructed that the bottom portion thereof serves as a heating pot.

What I claim and desire to protect by Letters Patent is:

1. IThe process of condensing formaldehyde with a liquid organic compound selected from the group consisting of saturated unsubstituted primary and secondary nitroparaiiins and saturated unsubstituted aliphatic ketones which have at least one hydrogen atom united with a carbon atom alpha to the carbonyl group to provide a monomethylol derivative of said organic compound, which process comprises introducing said organic compound into a fractionator, applying heat at the bottom portion of said fractionator` to vaporize said organic compound, passing the evolved vapors upwardly through the fractionator, said fractionator being operated under total reflux conditions but below the flood point of. the fractionator, owing formaldehyde and an alkaline catalyst downwardly through the fractionator and countercurrent to the upwardly flowing vapors of the organic compound, maintaining said fractionator at a temperature to cause said organic compound to react with said formaldehyde to form a monomethylol derivative of said organic compound, simultaneously rectifying the mixture of reactants and monomethylol derivative in the said fractionator to provide a progressively higher concentration of the monomethylol derivative downwardly through the fractionator, and withdrawing said monomethylol derivative from the bottom portion of said fractionator, the rate of now of said formaldehyde being such that there is an excess of said organic compound on a molar basis Within the reaction zone of the fractionator.

2. The process of condensing formaldehyde with a liquid organic compound selected from the group consisting of saturated unsubstituted primary and secondary nitroparans and saturated unsubstituted aliphatic ketones which have at least one hydrogen atom united with a carbon atom alpha to the carbonyl group to provide a monomethylol derivative of said organic cornpound, which process comprises introducing said organic compound into a fractionator, applying heat at the bottom portion of said fractionator to vaporize said organic compound, passing the evolved vapors upwardly through the fractionator, said fractionator being operated under total reflux conditions but below the flood point of the fractionator,- -lowing aqueous formaldehyde andan alkaline catalyst downwardly throughthe fractionator and countercurrent to the upwardly flowing vapors-'of the 4organic compound, maintaining said"fractionator. at a temperature to cause-said organic compound to reactl with said formaldehyde to form a monomethylol derivative of said Iorganic compound,y simultaneously :rectitying,` the `mixture of reactants and monomethylol derivative in the said'fractionator to provide a progressively higher concentration 'of themonomethylol 'derivative downwardlyy through the fractionator, and withdrawing said monomethylol lderivative fromthe bottom portion of said fractionator, the rateof ow -oi said formalde- J hyde -being suchthat thereis an excess of said organic compound on a molar basis within the reaction zone of thefractionator.

3; T-he process of'claim 2 wherein a saturated unsubstituted aliphatic ketone having at least one hydrogen atom united with a carbon atom alpha tofthe carbonyl group is employed as the liquid organic compound.

4. The process `of claim 3fwherein methyl ethyl ketone :is employed'` as the saturated unsubstituted aliphatic ketone.

5. The process of claim 4 wherein a mixture of aqueousformaldehyde and an alkaline catalyst having a pH betweenfaboutl' 9 and about 11-is flowed downwardly through the .fractionator 6.A Theprocess of claim5 whereinthe -rate of flow of the mixture of aqueous formaldehyde and alkaline catalyst is such that the molar ratio methyl ethyl ketone :formaldehydewithin the reaction -zone of the fractionatoris ati-least 30:1.

7. The process-of claim 3 wherein acetone is employed asthe saturated unsubstituted aliphatic ketone.

' 8. The process ofV claim 'l wherein a mixture of aqueous formaldehyde andan alkaline catalyst having a pH between about 9 Vand about 11 is owed downwardly through the fractionator.

9. The; process ofclaim 8 wherein the rate of flow of'the mixture of aqueous formaldehyde and alkaline catalyst is such that the Ymolar ratio acetone2formaldehydejwithin the reactionzone of the fractionator is atleast 55:1.

A10. The process of claim 2 wherein Vthe liquid organic compound employed-is a saturated unsubstituted nitroparaftin having at least one hydrogen atom united with the carbon atom to which the nitro group is attached.

11. The process of claim 10 wherein the nitroparaffin vemployed is nitromethane.

12. The process ofcondensing formaldehyde witha liquid organic compound selected' from the group consistingof saturated unsubstituted primary and secondary nitroparaflins and'saturated unsubstituted aliphatic. ketones which have at least one hydrogenatom united with a carbon atom alpha to ,the carbonyl group to provide a monomethyloLderivative of said organic compound, which process comprises introducing said organic compoundjnto a ,fractionation applying heat at the bottom portion of said fractionator to vaporize said organic compound, passing the evolved vapors upwardly through the fractionator, said fractionator being operated under total reflux conditions but-below. theood point of thefractionator, flowing formaldehydeand an alkaline. catalystuownwardly through the; fractionator and oountercurre'nt` to Atheupwardly ilow-ing vapors of the organic compound, maintaining said f-ractionator---at a temperature -to cause said organic compoundto react with said formaldehyde to for-m a monomethylol derivative ofsa'id organic compound, simultaneouslyrectifying-the mixture ofreactants and monomethyl'ol derivative in the said fractionator to provide a progressively higher-concentration of the monomethylol derivative downwardly lthrough *the fractionator; neutralizing in thebottom portion of said fractionator any alkaline catalyst present, and withdrawing said monomethylol 'derivative from theY bottom `portionfof said fractionator, the rate of now cf said formaldehyde being suchlthat there'is anfexcessl of s'aid'forganic-compound on a molarv basis withinthe-.reaction zone-ofthe fractionator.

Y'13."1he process of condensing `formaldehyde with aliquid organic compound-selected from the group consisting-"of saturated unsubstituted primary yand secondary nitroparains and' saturated unsubstituted aliphaticl ketones 'which have at least onehydrogen atom united with afcarbon atom alpha to 'the'v carbonyl group to provide a monon'iethylol derivative KV"ofsaid Aorganicvcompound, which process comprisesintroducing said organic' compound yinto a fractionator, applying heat at the bottomV portion of ysaid''fractionator to vaporize said organicy compound, passing the evolved vapors upwardlyithrou'gh the fractionator, said vfractionator-beingv'operated under total reflux .conditions but v-below the iiood point of the' fractionator,' flowing a mixture of aqueous formaldehyde and an 'alkaline 'catalyst ata pH between. about -9 and about 11 v'downwardly through the fractionator and countercurrent' to the upwardly' flowing vapors oi'the organic compound,'1naintaining said fractionator vat a yternperature to cause said organic-compound to react with said formaldehyde to' form amonometh'ylol derivative of said `organiccompound, simultaneously rectifying the rmixture of reactants=and monomethylol derivative'inthesaid fractionator to providel a'progres'sively higher concentration ofthe monom'ethylcl` derivative vdownwardly throughftl'leA fractionator, and withdrawing said monomethylol derivative' from the bottom portion of said-fractionator, :the rate of flow of said formaldehyde being-such'that'thereis an excess of said organic compound on a molar basis withinthe reaction zone of the' fractionator.

' HAROLD M. SPURLIN.

REFERENCES CITED The, following references are. of record in the le of, this., patent:

UNITED STATES PATENTS Number vName 'Date i 1,955,060 Flemingfet `al Apr. '17, 1934 2,130,592 McAllister fSept."20, l1938 2,132,352 Hass Oct."4, 1938 2,265,177 Lange vet al. "Dec.9,' 1941 2,378,573 `Natta June '19, 1945 2,395,414 Lincoln Febf'26, 1946 FOREIGN PATENTS Number Country Date I#58,068 Sweden -Jan. 7, 1925 

1. THE PROCESS OF CONDENSING FORMALDEHYDE WITH A LIQUID ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF SATURATED UNSUBSTITUTED PRIMARY AND SECONDARY NITROPARAFFINS AND SATURATED UNSUBSTITUTED ALIPHATIC KETONES WHICH HAVE AT LEAST ONE HYDROGEN ATOM UNITED WITH A CARBON ATOM ALPHA TO THE CARBONYL GROUP TO PROVIDE A MONOMETHYLOL DERIVATIVE OF SAID ORGANIC COMPOUND, WHICH PROCESS COMPRISES INTRODUCING SAID ORGANIC COMPOUND INTO A FRACTIONATOR, APPLYING HEAT AT THE BOTTOM PORTION OF SAID FRACTIONATOR TO VAPORIZE SAID ORGANIC COMPOUND, PASSING THE EVOLVED VAPORS UPWARDLY THROUGH THE FRACTIONATOR, SAID FRACTIONATOR BEING OPERATED UNDER TOTAL REFLUX CONDITIONS BUT BELOW THE FLOOD POINT OF THE FRACTIONATOR, FLOWING FORMALDEHYDE AND AN ALKALINE CATALYST DOWNWARDLY THROUGH THE FRACTIONATOR AND COUNTERCURRENT TO THE UPWARDLY FLOWING VAPORS OF THE ORGANIC COMPOUND, MAINTAINING SAID FRACTIONATOR AT A TEMPERATURE TO CAUSE SAID ORGANIC COMPOUND TO REACT WITH SAID FORMALDEHYDE TO FORM A MONOMETHYLOL DERIVATIVE OF SAID ORGANIC COOMPOUND, SIMULTANEOUSLY RECTIFYING THE MIXTURE OF REACTANTS AND MONOMETHYLOL DERIVATIVE IN THE SAID FRACTIONATOR TO PROVIDE A PREOGRESSIVELY HIGHER CONCENTRATION OF THE MONOMETHYLOL DERIVATIVE DOWNWARDLY THROUGH THE FRACTIONATOR, AND WITHDRAWING SAID MONOMETHYLOL DERIVATIVE FROM THE BOTTOM PORTION OF SAID FRACTIONATOR, THE RATE OF FLOW OF SAID FORMALDEHYDE BEING SUCH THAT THERE IS AN EXCESS OF SAID ORGANIC COMPOUND ON A MOLAR BASIS WITHIN THE REACTION ZONE OF THE FRACTIONATOR. 